Title (fr)

Publication

Application

Priority

US 9927604 W 19991119

US 10964898 P 19981124

US 26749999 A 19990312

US 28626299 A 19990405

US 34748699 A 19990702

Abstract (en)

[origin: WO0031014A1] The present invention provides a solvent extraction purification method for aromatic polycarboxylic acids or derivatives that meet or exceed polymer-grade specification. The method includes dissolving a crude aromatic polycarboxylic acid or derivative in a base compound; removing impurities and excessive base compound; and removing residual base compound while making purified product. The purification method removes not only the impurities from the crude acid or derivative, but also the residual base compound from finished product that otherwise will contaminate the product. The salt in the cake is converted to product by acid-substitution, thermal decomposition, or electrolysis. The method uses base-extraction solvents to extract base compound and impurities from the salt. The residual base compound in the recovered product is then removed by leaching, stripping, thermal agitating with electromagnetic waves, or evaporation with thermal decomposition. The purification method allows eliminating crystallizers for crystallization and equipment for drying and pneumatically carrying. Finally, the purification method is combined with the oxidation and solvent recovery in prior art to use only one set of process steps, instead of two, to produce aromatic polycarboxylic acids or derivatives.